An audio system has a connector with a signal pin that interfaces the audio system with an external device. An audio integrated circuit has a digital to analog converter (DAC) and an audio power amplifier having an input coupled to an output of the DAC and an output coupled to an output pin of the audio integrated circuit. Data storage contains stored instructions that program a processor to select an audio output mode of operation namely line-out mode or headphone mode. A configurable output conditioning circuit is coupled between the output pin of the audio integrated circuit and the signal pin of the connector. The conditioning circuit changes the output impedance that is presented at the signal pin, under control of the programmed processor when selecting the audio output mode of operation. Other embodiments are also described and claimed.